Circuit-controlling thermostat.



J. F. McELROY. CIRCUIT CONTROLLING THERMOSTAT. APPLICATION FILED JUNE 1,1911.

Patented June 3, 1913.

I W gin-v0 wtqz UNITED STATES PATENT OFFICE.

JAMES F. McELROY,OF ALBANY, NEW YORK, ASSIGNOR TOCONOLIDATED CAR-HEATING COMPANY, A CORPORATION OF WEST VIRGINIA.

CIRCUIT- CONTROLLING THERMOSTAT.

To all whom it may concern Be it known that I, JAMES F. MCE-LROY, acitizen of the United States, residing at Albany, county of Albany,State of-New York, have invented certain new and useful Improvements inCircuit-Controlling Thermostats, the following being a full, clear, andexact disclosure of the one form of my invention which I at present deempreferable.

For a detailed description ofthe present form of my invention, referencemay .be had to the following specification and to the accompanyingdrawings, which illustrate my invention.

The drawing shows a diagram of m thermostat and circuits controlledthereby.

My invention relates to a thermostat for controlling electric circuits,such, for instance, as an electric heater circuit, and it isparticularly designed to operate on circuits This contact block,

of high voltage which require that magnets connected thereto shall be ofhigh resistance and contain many turns of fine wire, so that it isinexpedient to maintain them constantly in circuit. The thermostatitself, including its maintaining coils, may however be employed in anyother situation for which it may be available.

Referring to the drawing which'shows the thermostat, the tongue tthereof is formed'of two strips of different metals such as brass andiron constituting a compound strip. Th iron strip in the thermostattongue is continued down opposite the poles of two magnets b and 6 whilethe brass strip terminates at a point above the 5 when deenergized saidpoles. By this means the iron portion of the tongue becomes anarmatureupon which f magnets may act. At its lowerand closes its circuit acrossthe contacts E E, 5 breaking at the same time the circuit at-contacts FE. Th which serves to ing the core K either 0f the extremity the tongueis provided with a German silver contact block adapted to touch one orthe other of the contact screws X Y which are passed through bothbranches of a loop of magnetic metal forming the magnetic pole pieces ofeach magnet, the loop actingby its slight resiliency to lock the screwin any position in together with the contact screws or terminals X and Yform two sets of contacts closed alternately by the thermostat.

For'illustrati'on I have shown the thermo- Specification of LettersPatent. Application filed June 1, 1911'.

at T.

thence through the which it may be set.

- Patented June 3, 1913. Serial No. 630,679.

stat as'operating on an electric heater eniployed for heating anapartment, such as a railway car. an electroma net, may be similarlycontrolled by tie thermostat. heater is indicated at H and thethermostat A is the main supply wire for the heater, which may bereferred to as the line side of the main circuit, and from this supplywire are also derived the thermostat-controlling circuits by which thecurrent to the heater is dominated. All of these circuits are controlledby the manual switch S. he circuit The electric Any other device, forinstance,

to the heater passes from the switch S to the dominating switch D andthence, when the dominating switch is closed, through the coil of amagnet C to the heater H From the switch S the circuit 1 leads to thetongue t of the thermostat T which makes Contact on either side with theterminals formed by the aforesaid screws X and Y of the two othercircuits marked 2' and 3 respectively which lead to the opposite side ofthe main circuit. Of these two circuits the former (2) passes throughthe small magnet 6 at the thermostat and goes thence to the sw'itcoperatin coil B and thence through the contacts controlled'by the coil-0, to the ground or opposite side of the main circuit. The other of thetwo circuits (3) passes through the small magnet b of the thermostat tothe switch-operating coil B and contacts F F, also controlled by thecoil C, to the heater. The

coil C, which may be termed the'goveniing coil, is shown as of thesolenoid form, and

and closes the circuit across the contacts F F, but when energized itscore is lifted e operating coil B is the one close the switch 1) bydrawto the right, and the operatlng coil B is the one which acts to openthe switch D by drawing the core K to the left.

The thermostat T will be exposed to the temperature of the apartmentwhose. heat is to be regulated, and its tongue a, so as the temperatureis at the desired normal point, will remain out of vcontact with both ofthe contact screws and ,Y. When the its core drops by gravity a long Ithe switch I) to open;

temperature rises, the tongue will move to the right against the contactscrew Y and thereby close the aforesaid circuit 2 through theswitch-opening coil B and so cause when the temperature to the leftagainst contact X and thereby close the aforesaid circuit 3 through theswitch-closing coil B In the latter event the circuit 3 will find thecontacts F F closed by the dropping of falls, it will move the core ofgoverning 0011 C, it being rewhich includes the governor coil C. The

governing coil will then lift its core to break, at contacts F F, thecircuit through the coil B which has just acted, and close the circuitat contacts E E through the circuit-opening coil B which will thereafter.be in a condition to operate and break the heater circuit as soon asits circuit 2 shall be closed at the right hand contact Y of thethermostat by a rise of temperature suflicient to require the cuttingout of the heater by the opening of switch D. The small magnets b bacting conj'ointly with the thermostat upon' the respective sets ofcontacts are of special value in situations where the thermostat issubject to vibrations as it is in a railway car. When the thermostattongue t touches the contacts X Y on either side, however mild thecontact may be made, the current instantly passes to the correspondingmagnet b or Z1 which acts to draw the tongue firmly against the contactand maintain it there until the operating coil 13 or B whose circuit hasbeen thereby closed, has acted and its circuit broken, as heretoforeexplained, by the governing-coil C. It should be noted that the coils Band B are wound with fine wire and have a considerable resistance. Thiswill reduce the current which the thermostat tongue has to carry to avery small amount, it being impracticable to make and break largecurrents by so delicate an instrument. If the voltage on the main lineis high, the resistance in the magnets B and B will require many turnsof the fine wire and render it undesirable to maintain them permanentlyin circuit, or in circuit longer than may be required for theiroperation of the switch D. By the use of the small retaining magnets 1and 11 1 am enabled to make a firm and certain contact between the"thermostat tongue and the contact screws X and Y for the transmissionof the small current that flows in the circuits which pass through thetongue.

"What I claim as new and desire to secure by Letters Patent is:

1. The combination with a thermostat having its movable member connectedto the line side of a grounded main circuit, mag:

nets, contacts carried by the pole pieces of the magnets and in circuitwith the latter, said magnets cooperating with the thermostat to controlthe circuit, circuit wires leading from said magnets to ground, a motorconnected with said wires so as to be reversely operated thereby, saidmain circuit controlled by said motor,-a switch for normally completingthe circuit through one of said wires to the motor when said thermostatis in engagement with one of said contacts, and magnetic meanscontrolled by the main circuit for operating said switch to complete thecircuit through the second wire to the motor when the thermostat is inengagement with the other contact, the circuit through one wire beingclosed by said switch simultaneously with the opening of the circuitthrough the other wire.

2. The combination with a grounded main electric circuit, of athermostat, a connection between one side of said circuit and themovable member of the thermostat, two 95 contacts either of which may beengaged by said movable member, two conductors leading from saidcontacts respectively, two retaining magnets for said movable membereach connected with one of the two conductors aforesaid, two oppositelyacting mag netic coils each of which is also connecte with one of thetwo conductors aforesaid, a switch controlled by said coils, and meanscontrolled by said switch for connecting either of said conductors tothe ground side of the main circuit.

3; The combination with a grounded main circuit, of a translating devicetherein, a switch controlling said device, circuits which shunt saidswitch, electro-magnets of high resistance included in said shuntcircuitsfor operating said switch, a thermostat having its contacttongue connected to the line side of said switch, contacts forming therespective terminals of said shunt circuits and arranged to be engagedalternately by said contact tongue, retaining magnets for said contacttongue one in each of saidshunt circuits, and a magnet in series withsaid translating device and controlling the shunt circuits.

at. The combination with a grounded main circuit, of a translatingdevice therein, a switch contrt'lling said device, circuits which shuntsaid switch and of which one is 'in series with said translating device,elect-romagnets of high resistance included in said shunt circuits foroperating said switch, a

nected to the line side of said switch, con- In witness whereof I havehereunto set tacts forming the respective terminals of my hand, beforetwo subscribing Witnesses, said Shunt circulits and agranged to beenthis 29th day of May, 1911.

gage a ternate y by sai contact tongue, retaining magnets for saidcontact tongue JAMES MCELROY one in each of said shunt circuits, and aWitnesses: magnet in series with said translating de- ERNEST D; JANSEN,Vice and controlling the shunt circuits. JOHN A. MCELVENEY.

